# Complex Responses to Climate Warming of Arctic‐Alpine Plant Populations From Different Geographic Provenance

## TL;DR

The study explores how arctic-alpine plants from different regions respond to warming and heat waves, finding that northern populations grow more and show higher resilience.

## Contribution

The study introduces a novel approach by integrating genetic variation and phenotypic plasticity in assessing climate resilience of arctic-alpine species.

## Key findings

- Northern provenance plants grew more than southern ones under warming conditions.
- The Swedish population showed the highest phenotypic plasticity linked to high genetic variation.
- Heat waves increased mortality, especially under drought conditions.

## Abstract

The distribution of ‘cold‐adapted’ plant species is expected to undergo severe range loss in the near future. Species distribution models predicting species' future distribution often do not integrate species ability to respond to environmental factors through genetic traits or phenotypic plasticity. This especially applies to arctic‐alpine species whose present‐day range is strongly fragmented because of the cyclic vicissitudes they experienced during the Ice Age. We cultivated plants from four European populations of the arctic‐alpine species
Viscaria alpina
from different geographic provenances. Two of the populations were from northern high‐latitude regions in Scandinavia; the remaining two populations were from southern mid‐latitude mountains. In both areas, one population was from a colder site and the other from a warmer site. We cultivated the plants in controlled thermal conditions with two treatments, one mimicking temperature conditions at the warmest site and the other adding 2 day‐temperature peaks mimicking short‐term heat waves. At the end of the experiment, we measured growth in length and mortality of all plants along with a set of ecophysiological variables. We also assessed phylogeographic variation in the four populations based on plastid‐DNA sequences. The plants from northern provenances grew more than those from the southern provenances. The plants of all populations performed overall well, in terms of growth rate and ecophysiology, under the heat spell, with the plants of the Swedish population exhibiting the highest phenotypic plasticity. Such a pattern was associated with the highest genetic variation in the Swedish population. Mortality of the plants cultivated under warm temperatures was overall low, but mortality strongly increased in the plants exposed to the heat spell. We conclude that plants of
V. alpina
populations from different geographic provenances are generally able to cope with scenarios resulting from global warming, but drought hampers resilience to heat waves through increased mortality.

The distribution of ‘cold‐adapted’ plant species is expected to undergo severe range loss in the near future. Arctic species are predicted to experience range contraction at their southern trailing‐edge locations. The distribution range of alpine species is expected to shrink at their lower‐elevation trailing‐edge locations. For arctic‐alpine species, it is conceptually difficult to evaluate the geographic location of trailing‐edge vs. leading‐edge populations because arctic‐alpine species underwent multiple re‐colonization events during the Pleistocene. We cultivated plants from four European populations of the arctic‐alpine species
Viscaria alpina
from different geographic provenances, two populations from high‐latitude regions and two populations from southern mid‐latitude mountains. The plants experienced two treatments, one mimicking temperature conditions at the warmest provenance site and the other adding 2 day‐temperature peaks mimicking short‐term heat waves. The plants of all populations performed overall well under both treatments, with the plants of the Swedish population exhibiting the highest phenotypic plasticity in association with high genetic variation. Mortality of the plants cultivated under warm temperatures was overall low, but mortality strongly increased in the plants exposed to the heat spell because of a detrimental drought effect.